How to wrap a spiral around an object?
Is it for a still or animate character? Here is a way to do it for a still character, I hope someone will give you a solution if you need to animate your character:


Model your character.
Create a bezier curve that loosely wraps around the shape of the leg. Put the bezier origin point on its bottom vertex, check its direction so that it goes up.
Give your bezier a Shrinkwrap modifier with the leg as Target, enable the fourth displaying option of the modifier (Apply this and all preceding deformation modifiers...).
Create a cylinder, subdivide it horizontally and put it on the origin point of the bezier.
Give it an Array and a Curve modifier, enable the Merge option of the Array, and choose the bezier as the Object of the Curve modifier. Play with the parameters so that it follows the bezier correctly. Give also your cylinder a Subdivision Surface modifier.
Play with the Offset of the bezier Shrinkwrap modifier to tighten the pipe along the leg.